1. Field of the Invention
The present invention relates to a method for film removal and an apparatus thereof, and more particularly, to a method for removing a film using plasma under atmospheric conditions and an apparatus thereof.
2. Description of the Prior Art
Processes of conventional liquid crystal display panels (TFT-LCD) entail switching between a dry process and a wet process repeatedly. In order to accelerate a process, panel manufacturers nowadays perform various processes of TFT-LCD in a dry environment, but it is still necessary to soak panels in photoresist strippers for removing photoresists.
Soaking a panel to remove a photoresist is followed by air-drying the panel, which incurs high manufacturing costs and prolongs the process. In light of the demand for large panels, the aforesaid drawbacks are becoming serious as panel size increases. In order to accelerate a panel process, some panel manufacturers remove photoresists by plasma. Plasma-based removal belongs to a dry process, thus a panel process can be completely carried out at a dry environment. As regards the yield, a process which involves removing a photoresists by soaking the photoresist-coated panel takes one hour to produce 75 pieces of panels. By contrast, the plasma-based photoresist removal process produces 100 to 120 pieces of panels.
Nevertheless, the plasma-based photoresist removal process has to be performed in a vacuum, and it entails continuously introducing gas and a catalyst in order to generate plasma. As a result, the yield increases, but so do the manufacturing costs.
In order to reduce the plasma production costs, Dainippon Screen Mfg. developed a technique whereby plasma is generated under atmospheric conditions to perform surface cleansing. Referring to FIG. 1A, an electric-field bias is generated across electrode plates 1a and 1b and configured to induce a reactant, gas A, to generate plasma. Referring to FIG. 1A again, a substrate 10 passes between the two electrode plates 1a and 1b and undergoes surface cleansing. The substrate 10 can be a fabric to be dyed or a material to be surface-mounted. Alternatively, the substrate 10 can be a liquid crystal panel from which a photoresist is to be removed by plasma.
Nonetheless, subjecting a liquid crystal panel to an electric field usually damages electronic components mounted on the liquid crystal panel. In this regard, Dainippon Screen Mfg. made the following improvements in the aforesaid atmospheric plasma-based surface cleansing technique. Referring to FIG. 1B which differs from FIG. 1B in that, instead of directly passing between the electrode plates 1a and 1b, the substrate 10 is disposed perpendicularly to the electrode plates 1a and 1b which cause plasma to be perpendicularly projected onto the substrate 10, and further, the substrate 10 is moved so as to react with the plasma thoroughly. The aforesaid improvements are open-ended, as it is feasible to modularize a plasma generation device such that the plasma generation device is turned into a plasma jet, for example.
In a situation where the substrate 10 is a photoresist-coated liquid crystal panel, plasma projected perpendicularly onto the liquid crystal panel removes most of the photoresist. However, part of the photoresist fails to react with the plasma but forms a particulate by-product. The by-product splashes and falls by gravity onto the panel, thus the panel yield is affected.
In order to solve the aforesaid drawbacks related to the by-product of the plasma reaction, some proposed installing a panel above a plasma generator for projecting plasma upwardly and vertically to the panel such that the splashed by-product spontaneously falls by gravity. Nevertheless, at a glance, the surfaces of liquid crystal panels are seemingly flat and smooth, they are full of plenty of microstructures indeed. In this regard, projecting plasma perpendicularly to a panel readily removes a photoresist from the fronts of the microstructures, but the perpendicularly projected plasma is unlikely to remove the photoresist from the lateral surfaces of the microstructures thoroughly. In addition, with the demand for large panels increasing, it is extremely inconvenient to invert large panels during a process. To alleviate the inconvenience, special hanging tools are designed to secure the panels in position but prove unsatisfactory because of high costs, not to mention that hanging large panels in the air is likely to bend the large panels. The aforesaid drawbacks also occur to U.S. Pat. No. 6,659,110 which discloses a method which involves disposing a substrate on a roller for solving problems with a by-product of a plasma reaction.
Accordingly, an issue that needs an urgent solution is related to endeavors to overcome the aforesaid drawback.